The Importance of Eggs
“… the immense, tender, terrible, heart-breaking, beauty and solemnity of Eggs.”
These words come from Frances Hodgson Burnett’s book, “The Secret Garden”. One of us had remembered the quote as “the importance of Eggs” (hence the title), but on re-reading a large chunk of the story to find the quote, discovered that memory plays tricks, or, possibly, that one of us unconsciously summarised the slightly overblown text.
The eggs in question are birds’ eggs. As you probably know, they belong to a pair of robins who inhabit the Secret Garden and play a significant and symbolic role in the tale of two children called Mary and Colin.
The book is very much of its time (first published by William Heinemann Ltd in 1911) and paints a picture of the life of rich and poor in India and England, of death from cholera and childbirth, of loved and unloved children, and of very clear distinctions in class and gender. Whether they be robins, landed gentry or moorland cottagers, the male is always in the lead!
But though we still love the lively tale of Mary and Colin, the obvious star of the book is the garden and the obvious hero, is, clearly, a robin. Both these characters could easily be in existence today. The secret garden of the Edwardian period could be re-cast as a neglected, 21st century open space, to be taken over by local community volunteers and made into a haven for all - human, plant and animal. The robin would still be the symbolic lead and, as it is hard to distinguish male and female robins, one would hope the symbolism could also be gender neutral!
But, we suggest, it is still impossible to apply such inclusiveness to eggs. What sort of eggs did you think of when you read the title of this blog? We bet you thought of birds’ eggs - probably hens’ eggs, but full marks if you imagined robins’ eggs. But of course many, many other types of animals lay eggs which hatch externally to the parent’s body. Reptiles, amphibians and fish are obvious examples. Even a few mammals – the duckbilled platypus and the echidna – are egg layers.
But we tend to ignore the insects. The vast majority of insect species lay eggs and the majority of animals on planet earth are insects. So yes, eggs are very important indeed. Insects, however, tend to be small creatures with exoskeletons (ie their skeletons are on the outside of their bodies) and no lungs. They rely on diffusion to transport oxygen and this, according to multiple websites, means that small is not only beautiful but essential for getting sufficient oxygen to where it needs to be. Please correct us if we are wrong but when one of us was of an age to be reading the “Secret Garden”, teachers were rather vague on the causes for the small size of modern insects.
As well as being small, insects are, by and large, considered to be, well, not particularly attractive. Butterflies and moths are, of course, an exception to this rule, if only for part of their convoluted life cycle. On the wing, we love them. We have a bit of a love/hate relationship with their caterpillar (larva) stage and probably don’t see or recognise their weird pupa packages, which do their best to stay immobile and hidden until the time is right for the imago – the adult butterfly – to emerge.
But eggs? When did you last see a butterfly egg?
From Terroir’s perspective, the answer to that one is ‘about ten days ago’. This is the time of year when groups of humans (usually, but not exclusively, male) can be seen standing in a row, staring fixedly at a hedge of blackthorn (Prunus spinosa). For most humans, the blackthorn has two periods of the year when it is of interest (spectacular white blossom in early spring and dark blue sloes in the autumn); January/February just doesn’t feature. But for the butterfly enthusiast, searching for the eggs of the Brown Hairstreak butterfly (Thecla betulae) is a post-Christmas rite of passage in areas (particularly in southern and south west England and south west Wales) where the blackthorn flourishes.
The female butterfly lays her tiny eggs at the end of summer/early autumn. She prefers sheltered, south or east facing bushes or hedgerows, and lays her white eggs (usually one, sometimes two, but rarely more) in the angle between blackthorn twigs.
Image right: female brown hairstreak, heavy with eggs © Richard Stephens
Madam Butterfly prefers a bush which has been fairly recently cut back, so that such axils are more easily accessible. One of the great threats to the brown hairstreak population, however, is landowners/managers who cut back all their hedges in the autumn or winter after the eggs are laid.
Our favourite egg hunting ground, Spynes Mere, is a small nature reserve in north east Surrey, based on a flooded former sand quarry and sandwiched between the M25, M23 and an active sand extraction site. It sounds less than attractive but, once you have zoned out of the hum of the motorways, it is a pleasing spot, popular with dog walkers and birders and, in season, blackberry pickers. We featured the Mere in August 2023 when the (by then mature) quarry reclamation hedgerows were offering a particularly bountiful and varied display of berries. At that time, the blackthorn is less obvious, clad in greenery which hides immature sloes and, one hopes, plenty of twigs in a suitable condition for brown hairstreak egg laying.
Spynes Mere: above left -in summer garb; berries attract the humans, and the unassuming leafy blackthorn is attracting egg laden female brown hairstreaks
centre - winter reveals the young blackthorn regrowth; this is when and where the egg hunting takes place
right - a sprig of blackthorn displaying the multiplicity of twiggy angles which are so well hidden to the human eye in summer
And here the eggs are (below) - revealed to the eager searching eye (and possibly hand lens) of a butterfly watcher in January, and hugely magnified by the camera lense to reveal their fascinating sculptural form.
The eggs hatch in the late spring, after blossom time is over and about 7 to 9 days after leaf-bud burst begins (Life cycles of British and Irish butterflies, Peter Eeles, 2017, Pisces Publications). Eeles refers to a study by H H de Vries et al which links egg hatching with blackthorn leafbud burst, rather than air temperature, a charactristic which may help to future proof them against climate change. The caterpillar, having somehow received a message about leaf emergence, eats a neat round hole in the top of the egg shell and crawls into the developing leaf bud to start its journey to the pupa stage, before the final emergence of the butterfly in summer.
As you can imagine, the caterpillars are hard to see within their bushy hideout. But did you know that some caterpillars are fluorescent?! Hunting brown hairstreak caterpillars with a UV light reveals the eerie, blue phantom, below left. Below right is what you see with a more tradional light source. It is obvious which is the easier way of spotting a brown hairstreak larva!
Around June or July, the leaf fattened caterpillar starts to turn a pinkie-purple colour and heads for the leaf litter at the foot of its blackthorn bush haven. Here the creature pupates into another well camouflaged form - a small brown chrysalis (https://www.ukbutterflies.co.uk/species.php?species=betulae is excellent, with superb illustrations of all life cycle stages).
After about four weeks, the adult butterfly will finally emerge and forsake the blackthorn for the haven of a well grown ash tree (known as the Master Tree), to feed on honey dew and search for a mate. It will also become very difficult to photograph but here are some of our better efforts, from when they do come within reach.
This dependance of the species on a single Ash presents two challenges to 21st century society. First of all, some of us might well prefer to re-name the chosen ash as the prime, lead, pivotal, premier or home tree! But whatever we call it, dependance on Ash presents, potentially, a real problem to the Brown Hairstreak. We mentioned, above, the climate change advantage of caterpillar emergence depending on bud break rather than temperature. In southern England, however, Ash populations are being decimated by the fungal disease known as Ash dieback, and in the short term, the impact is severe with enormous numbers of ash dead, dying or already felled.
So next time anybody asks what something has to do with the ‘price of eggs’, don’t think of hens, robins or echidnas. Spare a thought for all the insects who struggle through complicated lifecycles to ensure their eggs make it to adulthood.
Image right: © Richard Stephens